Detergent compositions for fabric or hard surface cleaning typically comprise a surfactant system whose role is to assist in removal of soil. For fabric and hard surface cleaning, the surfactant system is often composed predominantly of non-soap surfactants.
Detergent compositions in the solid form are much cheaper than liquids because of low cost packaging and these are very popular forms for developing countries. The product dosage in the solid form is easier, it avoids spillage and the product application can be better controlled. Amongst the solid form, bars are gaining popularity and growing rapidly in the developing markets because of better value delivery. Cleaning compositions in the bar form are economically superior to other product forms and the dosage per swipe from the bar is highly controlled.
Detergent bars require an acceptable physical strength so that they retain their structural integrity during handling, transport and use. Various abrasives, fillers, builders, and other ingredients such as colour, perfume, preservatives, etc. may also be incorporated suitably.
Detergent bars for fabric and hard surface cleaning are in constant contact with water during usage and often during subsequent storage as well and hence get sogged and generally disintegrate to paste form. The shape and contour of the bars is not retained satisfactorily.
This problem is generally attempted to be solved by making suitable changes in the formulation of the bar. Any attempt to harden the bar, if not properly controlled through formulation, can result into a too hard product that would not release sufficient product for cleaning. Therefore, it is a major challenge to ensure that a) there is no disintegration of the product during use, b) there is no wastage of product through mush generation, and c) yet the product is sufficiently soft to enable the user to pick up the right quantity of product while cleaning.
In our co-pending application 417/Mum/2001, we have described a direct application, shaped detergent product which comprises a water-resistant coating that is capable of being abraded from the detergent product during use. Preferably, the shaped detergent product is an extruded bar and comprises an abrasive, wherein the external surface of the said detergent bar comprises one or more materials having a permeability coefficient for water less than   1000  ×            10              -        13              ·                            [                      Cm            3                    ]                ⁡                  [          Cm          ]                                                  [                          Cm              2                        ]                    ⁡                      [            s            ]                          ⁡                  [          Pa          ]                    and with a melting point greater than 30° C., wherein [Cm3]=Cm3(273, 15K; 1,013×105 Pa.), as outlined in “Polymer Handbook, 1989, Third edition, Eds. J. Brandrup and E. H. Immergut, (Wiley-Interscience Publication), page VI/436”.
Polymer coatings for protecting surfaces are known in literature. Polymer coating can be achieved by melt coating, solvent coating or radiation or thermal curing of liquid coating.
Radiation cured polymer films are known in the art and provide fast curing. Polymer film properties can be controlled by adjusting the polymer composition. Such coatings are amenable to various types of application methodology including spray, dip and brush coating.
Thus, photo-curable resin compositions (U.S. Pat. No. 5,213,875, Westinghouse, 1993), are used as topcoats on various objects and are formulated to provide scratch resistance, abrasion resistance, stain resistance, thermal stability, chemical and weather resistance to the coated object.
U.S. Pat. No. 6,284,835 (Lilly Indus. 2001), teaches curable coatings that exhibit high resistance to impact damage and are specifically applicable to sporting goods and equipment such as golf balls, vehicle bumpers and other surfaces.
U.S. Pat. No. 6,293,287 (Gillette, 2001) discloses the method of producing dental floss coated with a UV-cured resin to provide improved abrasion resistance.
However, none of the prior art teaches the use of these radiation curable resins to improve the durability of articles such as detergent compositions or other objects that are in continuous contact with water.